1. Field of the Invention
The invention relates to a linear actuator comprising a cabinet, an electric motor, a transmission, a gear housing, containing at least part of the transmission, a spindle, connected to the electric motor via the transmission, on which spindle is mounted a spindle nut.
2. The Prior Art
Linear actuators are widely used within many different areas, e.g. in connection with adjustable furniture, control systems, machines etc. Some of the qualities of a linear actuator are that it is maintenance-free, compact, sturdy and easy to install. Implicitly, these qualities also result in limitations in connection with adapting the actuator to the construction in which it is to be incorporated. It would often be expedient if the actuator, besides driving the spindle nut back and forth, could also be fitted with optional equipment. As an example of optional equipment may be mentioned a switch or a system for position determination of the spindle nut during its travel on the spindle.
EP 0 831 250 to Danaher Corporation discloses a linear actuator in which a rotary potentiometer is incorporated.
A rotary potentiometer is a fine way to equip an actuator with a system for position determination. However, a more flexible system could be desirable, as the potentiometer is deeply integrated in the construction, so that it is not immediately possible to replace or change over to other types of optional equipment.